A work vehicle mounts an engine, a speed changer device, etc. for driving a utility implement and a traveling device. Thus, in a circuit of e.g. lubricant oil, there is incorporated an oil equipment such as an oil filter. From such oil equipment, oil is discharged at the time of operation or maintenance inspection. From U.S. Pat. No. 5,386,881, there is known a grass mower machine configured such that oil is discharged to an outside of a blade housing by means of an expandable/contractible (telescopic) oil drain device that extends from an oil sump of an engine. This oil drain device consists of an outer tube fixed to the blade housing and an inner tube which moves like a piston within the outer tube. When oil is to be discharged, the inner tube will be drawn out of the outer tube until its leading end is exposed sideways from the blade housing. When not used, the inner tube will be fixedly threaded to the outer tube by a lock nut.
An oil drain device according to U.S. Pat. No. 6,427,427 comprises an oil drain valve formed integral with an engine mount flange attached to a top wall of a mower deck. An inlet of the oil drain valve is communicated to an oil sump formed in the engine mount flange. Oil exiting an outlet of this oil drain valve is discharged to the inside of the mower deck via a through hole defined n the mower deck.